All Spridget front disc brake calipers are the same and thus they use the same rebuild kit. Each kit includes all the seals needed to do both pistons in one caliper. Easy to install with no special tools required. Late Minis with 12" wheels and 8.4" brakes also use this larger caliper.2 kits required per car. For the seal between the caliper halves use 17H7679.Fits GBC18 and GBC141 calipers.